FERGUSON, Mo. (AP) — Protests in the St. Louis suburb rocked by racial unrest since a white police officer shot an unarmed black teenager to death turned violent Wednesday night, with some people lobbing Molotov cocktails and other objects at police who responded with smoke bombs and tear gas to disperse the crowd.

Ferguson Police Chief Thomas Jackson, who has been the public face of the city torn by Saturday’s death of 18-year-old Michael Brown, told reporters earlier in the day that the St. Louis County investigation of the shooting could take weeks to complete. In the meantime, he said, his department welcomes Justice Department training on racial relations in the suburb, where two-thirds of the 21,000 residents are black while all but three of the police force’s 53 officers are white.

“Unfortunately, an undertow (of racial unrest) has bubbled to the surface,” said Jackson. “Race relations is the top priority right now.”

While Jackson said he wanted to mend fences with the community, protesters were on the streets of Ferguson again Wednesday, facing heavily armed police who at time trained weapons on them from an armored truck. Two reporters said they were detained by police while working at a McDonald’s in the area.

The situation became more tense after nightfall, with police ordering people to go home and then using smoke bombs and later tear gas after some people threw Molotov cocktails and other things at them. Most of the crowd then dispersed. Journalists who witnessed the events included an Associated Press photographer.

St. Louis County police spokesman Brian Schellman said he had no immediate information about the situation.

Earlier, Wesley Lowery of The Washington Post and Ryan Reilly of The Huffington Post said they were handcuffed and put into a police van after officers came in to quickly clear the fast-food restaurant where they were doing some work. The Washington Post reported that Lowery said he was slammed against a soda machine and plastic cuffs were put on his wrists. Reilly told MSNBC that an officer slammed his head against the glass “purposefully” on the way out of the restaurant “and then sarcastically apologized for it.” The reporters were subsequently released without any charges.

Martin D. Baron, The Washington Post’s executive editor, issued a statement saying “there was absolutely no justification” for Lowery’s arrest and said the organization was appalled by the officers’ conduct.

Ryan Grim, Washington, D.C., bureau chief for The Huffington Post, said in a statement that “compared to some others who have come into contact with the police department, they came out relatively unscathed, but that in no way excuses the false arrest or the militant aggression toward these journalists.”

Jackson did not immediately return a cellphone message Wednesday night from the AP seeking comment about the arrests.

The mystery of the officer’s identity has fanned the discord, with Jackson arguing that revealing that detail could bring retribution to the officer whose life since Saturday has been countlessly threatened.

But civil rights activists and the attorney for Brown’s family, all pressing for calm amid nights of unrest since Brown’s death, counter that knowing the officer’s name may help the area to heal, allowing the National Association for the Advancement of Colored People and others to dig into the officer’s background for any prior brutality.